Multi-level modulation schemes, such as one in the QPSK or the 16-QAM, are known as one type of modulation schemes for the wireless communication technique. In multi-level modulation schemes, a transmission bit string that is encoded using an error correction code, such as a turbo code, is mapped to a multi-level modulation signal (symbol). In the case of the 16-QAM, since one symbol is made up of four bits, a transmission bit string is mapped to one of the four bits.
In addition, the HARQ is known as one of elemental techniques for wireless communication techniques, such as the High Speed Downlink Packet Access (HSDPA) (see Non-Patent Document 1 that is listed below, for example). The HARQ is the technique in which data, a reception of which failed, is retained, instead of discarding it at the receiving party, and the data is decoded (error correction decoded) together with other data sent from the transmitting party. In this manner, the gain in error correction code is increased and thus reducing the retransmission count even when an error occurs, by effectively utilizing data that has been received.
Furthermore, the MIMO is known as one technique for wireless communications. The MIMO is a technique to improve the transmission rate without requiring an increase in the frequency band, in which multiple antennas are used for both transmission and reception, dependent data streams are sent from multiple antennas of the transmitter, and multiple signals (data stream) that are mixed on the transmission path (channel) are separated from each other from signals received by each reception antenna of the receiver.
Note that Patent Document 1 that is listed below describes that the error resilience of code division blocks are deviated caused by the signal point arrangement of multi-level modulation signals and the uniformity in the quality among the blocks may be reduced. Thus, it is possible to make the error resilience among blocks to approach evenly by manipulating (controlling) a transmission bit string such that the occupying rate of organizational bit (or redundant bit) included in each block approaches evenly.    Patent Document 1: Japanese Laid-Open Patent Application No. 2005-229319    Non-Patent Document 1: 3GPP TS 25.212 V7.4.0 (2007-03)